Compacting machines or compactors are commonly used to compact work materials (such as soil, gravel, asphalt, landfill trash) to a desired density while constructing buildings, highways, parking lots, and other structures. In addition, compactors are often used to compact recently moved and/or relatively soft materials at mining sites and landfills. The process often requires a plurality of passes over the work material to reach the desired density.
Determining whether the desired level of compaction has been reached is often estimated in a variety of manners. In some instances, the compaction may be approximated by determining the ability of the work material to support a machine. For example, the penetration depth of toothed wheels of a compactor may be monitored as the teeth will penetrate less as the work material becomes more compacted. Other systems are also used to determine the ability of the work material to support a machine.
These systems typically determine the relative state of compaction of the work material. In other words, the systems determine the extent to which the work material has been compacted relative to the maximum compaction capacity or capability of the machine. As a result, the systems may determine that a work material has been compacted to some percentage of the maximum compacting capability of the machine. However, such systems do not provide an absolute or empirical measure of the state of compaction.
As a result, operators must perform secondary tests or evaluations at the work site to determine the actual state of compaction of the work material. Some of the secondary tests require the removal of material from an otherwise finished work surface. In addition, it may be necessary to perform tests at multiple locations to determine whether the desired level of compaction has been uniformly achieved.
U.S. Pat. No. 7,581,452 discloses a system in which distance measuring devices or sensors may be mounted to a vehicle and used to determine the distance between the sensors and the soil surface upon which the vehicle is operating. The distance from the sensors to the surface may be measured at locations at which the vehicle has traveled as well as locations at which the vehicle has not traveled. The measurements may be compared to determine the depth of a track made by the tire or wheel of a vehicle as the vehicle traveled along on the soil. The depth of the track may be used to calculate strength of the soil.
The foregoing background discussion is intended solely to aid the reader. It is not intended to limit the innovations described herein, nor to limit or expand the prior art discussed. Thus, the foregoing discussion should not be taken to indicate that any particular element of a prior system is unsuitable for use with the innovations described herein, nor is it intended to indicate that any element is essential in implementing the innovations described herein. The implementations and application of the innovations described herein are defined by the appended claims.